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lwip/netif/ppp/randm.c@0:d7bd7384a37c, 2016-12-07 (annotated)

Committer:
grzemich
Date:
Wed Dec 07 23:47:50 2016 +0000
Revision:
0:d7bd7384a37c
dgd

Who changed what in which revision?

UserRevisionLine numberNew contents of line
grzemich 0:d7bd7384a37c 1 /*****************************************************************************
grzemich 0:d7bd7384a37c 2 * randm.c - Random number generator program file.
grzemich 0:d7bd7384a37c 3 *
grzemich 0:d7bd7384a37c 4 * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
grzemich 0:d7bd7384a37c 5 * Copyright (c) 1998 by Global Election Systems Inc.
grzemich 0:d7bd7384a37c 6 *
grzemich 0:d7bd7384a37c 7 * The authors hereby grant permission to use, copy, modify, distribute,
grzemich 0:d7bd7384a37c 8 * and license this software and its documentation for any purpose, provided
grzemich 0:d7bd7384a37c 9 * that existing copyright notices are retained in all copies and that this
grzemich 0:d7bd7384a37c 10 * notice and the following disclaimer are included verbatim in any
grzemich 0:d7bd7384a37c 11 * distributions. No written agreement, license, or royalty fee is required
grzemich 0:d7bd7384a37c 12 * for any of the authorized uses.
grzemich 0:d7bd7384a37c 13 *
grzemich 0:d7bd7384a37c 14 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
grzemich 0:d7bd7384a37c 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
grzemich 0:d7bd7384a37c 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
grzemich 0:d7bd7384a37c 17 * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
grzemich 0:d7bd7384a37c 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
grzemich 0:d7bd7384a37c 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
grzemich 0:d7bd7384a37c 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
grzemich 0:d7bd7384a37c 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
grzemich 0:d7bd7384a37c 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
grzemich 0:d7bd7384a37c 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
grzemich 0:d7bd7384a37c 24 *
grzemich 0:d7bd7384a37c 25 ******************************************************************************
grzemich 0:d7bd7384a37c 26 * REVISION HISTORY
grzemich 0:d7bd7384a37c 27 *
grzemich 0:d7bd7384a37c 28 * 03-01-01 Marc Boucher <marc@mbsi.ca>
grzemich 0:d7bd7384a37c 29 * Ported to lwIP.
grzemich 0:d7bd7384a37c 30 * 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
grzemich 0:d7bd7384a37c 31 * Extracted from avos.
grzemich 0:d7bd7384a37c 32 *****************************************************************************/
grzemich 0:d7bd7384a37c 33
grzemich 0:d7bd7384a37c 34 #include "lwip/opt.h"
grzemich 0:d7bd7384a37c 35
grzemich 0:d7bd7384a37c 36 #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
grzemich 0:d7bd7384a37c 37
grzemich 0:d7bd7384a37c 38 #include "md5.h"
grzemich 0:d7bd7384a37c 39 #include "randm.h"
grzemich 0:d7bd7384a37c 40
grzemich 0:d7bd7384a37c 41 #include "ppp.h"
grzemich 0:d7bd7384a37c 42 #include "pppdebug.h"
grzemich 0:d7bd7384a37c 43
grzemich 0:d7bd7384a37c 44 #include <string.h>
grzemich 0:d7bd7384a37c 45
grzemich 0:d7bd7384a37c 46 #if MD5_SUPPORT /* this module depends on MD5 */
grzemich 0:d7bd7384a37c 47 #define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
grzemich 0:d7bd7384a37c 48
grzemich 0:d7bd7384a37c 49 /*****************************/
grzemich 0:d7bd7384a37c 50 /*** LOCAL DATA STRUCTURES ***/
grzemich 0:d7bd7384a37c 51 /*****************************/
grzemich 0:d7bd7384a37c 52 static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
grzemich 0:d7bd7384a37c 53 static long randCount = 0; /* Pseudo-random incrementer */
grzemich 0:d7bd7384a37c 54
grzemich 0:d7bd7384a37c 55
grzemich 0:d7bd7384a37c 56 /***********************************/
grzemich 0:d7bd7384a37c 57 /*** PUBLIC FUNCTION DEFINITIONS ***/
grzemich 0:d7bd7384a37c 58 /***********************************/
grzemich 0:d7bd7384a37c 59 /*
grzemich 0:d7bd7384a37c 60 * Initialize the random number generator.
grzemich 0:d7bd7384a37c 61 *
grzemich 0:d7bd7384a37c 62 * Since this is to be called on power up, we don't have much
grzemich 0:d7bd7384a37c 63 * system randomess to work with. Here all we use is the
grzemich 0:d7bd7384a37c 64 * real-time clock. We'll accumulate more randomness as soon
grzemich 0:d7bd7384a37c 65 * as things start happening.
grzemich 0:d7bd7384a37c 66 */
grzemich 0:d7bd7384a37c 67 void
grzemich 0:d7bd7384a37c 68 avRandomInit()
grzemich 0:d7bd7384a37c 69 {
grzemich 0:d7bd7384a37c 70 avChurnRand(NULL, 0);
grzemich 0:d7bd7384a37c 71 }
grzemich 0:d7bd7384a37c 72
grzemich 0:d7bd7384a37c 73 /*
grzemich 0:d7bd7384a37c 74 * Churn the randomness pool on a random event. Call this early and often
grzemich 0:d7bd7384a37c 75 * on random and semi-random system events to build randomness in time for
grzemich 0:d7bd7384a37c 76 * usage. For randomly timed events, pass a null pointer and a zero length
grzemich 0:d7bd7384a37c 77 * and this will use the system timer and other sources to add randomness.
grzemich 0:d7bd7384a37c 78 * If new random data is available, pass a pointer to that and it will be
grzemich 0:d7bd7384a37c 79 * included.
grzemich 0:d7bd7384a37c 80 *
grzemich 0:d7bd7384a37c 81 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
grzemich 0:d7bd7384a37c 82 */
grzemich 0:d7bd7384a37c 83 void
grzemich 0:d7bd7384a37c 84 avChurnRand(char *randData, u32_t randLen)
grzemich 0:d7bd7384a37c 85 {
grzemich 0:d7bd7384a37c 86 MD5_CTX md5;
grzemich 0:d7bd7384a37c 87
grzemich 0:d7bd7384a37c 88 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
grzemich 0:d7bd7384a37c 89 MD5Init(&md5);
grzemich 0:d7bd7384a37c 90 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
grzemich 0:d7bd7384a37c 91 if (randData) {
grzemich 0:d7bd7384a37c 92 MD5Update(&md5, (u_char *)randData, randLen);
grzemich 0:d7bd7384a37c 93 } else {
grzemich 0:d7bd7384a37c 94 struct {
grzemich 0:d7bd7384a37c 95 /* INCLUDE fields for any system sources of randomness */
grzemich 0:d7bd7384a37c 96 char foobar;
grzemich 0:d7bd7384a37c 97 } sysData;
grzemich 0:d7bd7384a37c 98
grzemich 0:d7bd7384a37c 99 /* Load sysData fields here. */
grzemich 0:d7bd7384a37c 100 MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
grzemich 0:d7bd7384a37c 101 }
grzemich 0:d7bd7384a37c 102 MD5Final((u_char *)randPool, &md5);
grzemich 0:d7bd7384a37c 103 /* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
grzemich 0:d7bd7384a37c 104 }
grzemich 0:d7bd7384a37c 105
grzemich 0:d7bd7384a37c 106 /*
grzemich 0:d7bd7384a37c 107 * Use the random pool to generate random data. This degrades to pseudo
grzemich 0:d7bd7384a37c 108 * random when used faster than randomness is supplied using churnRand().
grzemich 0:d7bd7384a37c 109 * Note: It's important that there be sufficient randomness in randPool
grzemich 0:d7bd7384a37c 110 * before this is called for otherwise the range of the result may be
grzemich 0:d7bd7384a37c 111 * narrow enough to make a search feasible.
grzemich 0:d7bd7384a37c 112 *
grzemich 0:d7bd7384a37c 113 * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
grzemich 0:d7bd7384a37c 114 *
grzemich 0:d7bd7384a37c 115 * XXX Why does he not just call churnRand() for each block? Probably
grzemich 0:d7bd7384a37c 116 * so that you don't ever publish the seed which could possibly help
grzemich 0:d7bd7384a37c 117 * predict future values.
grzemich 0:d7bd7384a37c 118 * XXX Why don't we preserve md5 between blocks and just update it with
grzemich 0:d7bd7384a37c 119 * randCount each time? Probably there is a weakness but I wish that
grzemich 0:d7bd7384a37c 120 * it was documented.
grzemich 0:d7bd7384a37c 121 */
grzemich 0:d7bd7384a37c 122 void
grzemich 0:d7bd7384a37c 123 avGenRand(char *buf, u32_t bufLen)
grzemich 0:d7bd7384a37c 124 {
grzemich 0:d7bd7384a37c 125 MD5_CTX md5;
grzemich 0:d7bd7384a37c 126 u_char tmp[16];
grzemich 0:d7bd7384a37c 127 u32_t n;
grzemich 0:d7bd7384a37c 128
grzemich 0:d7bd7384a37c 129 while (bufLen > 0) {
grzemich 0:d7bd7384a37c 130 n = LWIP_MIN(bufLen, RANDPOOLSZ);
grzemich 0:d7bd7384a37c 131 MD5Init(&md5);
grzemich 0:d7bd7384a37c 132 MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
grzemich 0:d7bd7384a37c 133 MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
grzemich 0:d7bd7384a37c 134 MD5Final(tmp, &md5);
grzemich 0:d7bd7384a37c 135 randCount++;
grzemich 0:d7bd7384a37c 136 MEMCPY(buf, tmp, n);
grzemich 0:d7bd7384a37c 137 buf += n;
grzemich 0:d7bd7384a37c 138 bufLen -= n;
grzemich 0:d7bd7384a37c 139 }
grzemich 0:d7bd7384a37c 140 }
grzemich 0:d7bd7384a37c 141
grzemich 0:d7bd7384a37c 142 /*
grzemich 0:d7bd7384a37c 143 * Return a new random number.
grzemich 0:d7bd7384a37c 144 */
grzemich 0:d7bd7384a37c 145 u32_t
grzemich 0:d7bd7384a37c 146 avRandom()
grzemich 0:d7bd7384a37c 147 {
grzemich 0:d7bd7384a37c 148 u32_t newRand;
grzemich 0:d7bd7384a37c 149
grzemich 0:d7bd7384a37c 150 avGenRand((char *)&newRand, sizeof(newRand));
grzemich 0:d7bd7384a37c 151
grzemich 0:d7bd7384a37c 152 return newRand;
grzemich 0:d7bd7384a37c 153 }
grzemich 0:d7bd7384a37c 154
grzemich 0:d7bd7384a37c 155 #else /* MD5_SUPPORT */
grzemich 0:d7bd7384a37c 156
grzemich 0:d7bd7384a37c 157 /*****************************/
grzemich 0:d7bd7384a37c 158 /*** LOCAL DATA STRUCTURES ***/
grzemich 0:d7bd7384a37c 159 /*****************************/
grzemich 0:d7bd7384a37c 160 static int avRandomized = 0; /* Set when truely randomized. */
grzemich 0:d7bd7384a37c 161 static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
grzemich 0:d7bd7384a37c 162
grzemich 0:d7bd7384a37c 163
grzemich 0:d7bd7384a37c 164 /***********************************/
grzemich 0:d7bd7384a37c 165 /*** PUBLIC FUNCTION DEFINITIONS ***/
grzemich 0:d7bd7384a37c 166 /***********************************/
grzemich 0:d7bd7384a37c 167 /*
grzemich 0:d7bd7384a37c 168 * Initialize the random number generator.
grzemich 0:d7bd7384a37c 169 *
grzemich 0:d7bd7384a37c 170 * Here we attempt to compute a random number seed but even if
grzemich 0:d7bd7384a37c 171 * it isn't random, we'll randomize it later.
grzemich 0:d7bd7384a37c 172 *
grzemich 0:d7bd7384a37c 173 * The current method uses the fields from the real time clock,
grzemich 0:d7bd7384a37c 174 * the idle process counter, the millisecond counter, and the
grzemich 0:d7bd7384a37c 175 * hardware timer tick counter. When this is invoked
grzemich 0:d7bd7384a37c 176 * in startup(), then the idle counter and timer values may
grzemich 0:d7bd7384a37c 177 * repeat after each boot and the real time clock may not be
grzemich 0:d7bd7384a37c 178 * operational. Thus we call it again on the first random
grzemich 0:d7bd7384a37c 179 * event.
grzemich 0:d7bd7384a37c 180 */
grzemich 0:d7bd7384a37c 181 void
grzemich 0:d7bd7384a37c 182 avRandomInit()
grzemich 0:d7bd7384a37c 183 {
grzemich 0:d7bd7384a37c 184 #if 0
grzemich 0:d7bd7384a37c 185 /* Get a pointer into the last 4 bytes of clockBuf. */
grzemich 0:d7bd7384a37c 186 u32_t *lptr1 = (u32_t *)((char *)&clockBuf[3]);
grzemich 0:d7bd7384a37c 187
grzemich 0:d7bd7384a37c 188 /*
grzemich 0:d7bd7384a37c 189 * Initialize our seed using the real-time clock, the idle
grzemich 0:d7bd7384a37c 190 * counter, the millisecond timer, and the hardware timer
grzemich 0:d7bd7384a37c 191 * tick counter. The real-time clock and the hardware
grzemich 0:d7bd7384a37c 192 * tick counter are the best sources of randomness but
grzemich 0:d7bd7384a37c 193 * since the tick counter is only 16 bit (and truncated
grzemich 0:d7bd7384a37c 194 * at that), the idle counter and millisecond timer
grzemich 0:d7bd7384a37c 195 * (which may be small values) are added to help
grzemich 0:d7bd7384a37c 196 * randomize the lower 16 bits of the seed.
grzemich 0:d7bd7384a37c 197 */
grzemich 0:d7bd7384a37c 198 readClk();
grzemich 0:d7bd7384a37c 199 avRandomSeed += *(u32_t *)clockBuf + *lptr1 + OSIdleCtr
grzemich 0:d7bd7384a37c 200 + ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
grzemich 0:d7bd7384a37c 201 #else
grzemich 0:d7bd7384a37c 202 avRandomSeed += sys_jiffies(); /* XXX */
grzemich 0:d7bd7384a37c 203 #endif
grzemich 0:d7bd7384a37c 204
grzemich 0:d7bd7384a37c 205 /* Initialize the Borland random number generator. */
grzemich 0:d7bd7384a37c 206 srand((unsigned)avRandomSeed);
grzemich 0:d7bd7384a37c 207 }
grzemich 0:d7bd7384a37c 208
grzemich 0:d7bd7384a37c 209 /*
grzemich 0:d7bd7384a37c 210 * Randomize our random seed value. Here we use the fact that
grzemich 0:d7bd7384a37c 211 * this function is called at *truely random* times by the polling
grzemich 0:d7bd7384a37c 212 * and network functions. Here we only get 16 bits of new random
grzemich 0:d7bd7384a37c 213 * value but we use the previous value to randomize the other 16
grzemich 0:d7bd7384a37c 214 * bits.
grzemich 0:d7bd7384a37c 215 */
grzemich 0:d7bd7384a37c 216 void
grzemich 0:d7bd7384a37c 217 avRandomize(void)
grzemich 0:d7bd7384a37c 218 {
grzemich 0:d7bd7384a37c 219 static u32_t last_jiffies;
grzemich 0:d7bd7384a37c 220
grzemich 0:d7bd7384a37c 221 if (!avRandomized) {
grzemich 0:d7bd7384a37c 222 avRandomized = !0;
grzemich 0:d7bd7384a37c 223 avRandomInit();
grzemich 0:d7bd7384a37c 224 /* The initialization function also updates the seed. */
grzemich 0:d7bd7384a37c 225 } else {
grzemich 0:d7bd7384a37c 226 /* avRandomSeed += (avRandomSeed << 16) + TM1; */
grzemich 0:d7bd7384a37c 227 avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
grzemich 0:d7bd7384a37c 228 }
grzemich 0:d7bd7384a37c 229 last_jiffies = sys_jiffies();
grzemich 0:d7bd7384a37c 230 }
grzemich 0:d7bd7384a37c 231
grzemich 0:d7bd7384a37c 232 /*
grzemich 0:d7bd7384a37c 233 * Return a new random number.
grzemich 0:d7bd7384a37c 234 * Here we use the Borland rand() function to supply a pseudo random
grzemich 0:d7bd7384a37c 235 * number which we make truely random by combining it with our own
grzemich 0:d7bd7384a37c 236 * seed which is randomized by truely random events.
grzemich 0:d7bd7384a37c 237 * Thus the numbers will be truely random unless there have been no
grzemich 0:d7bd7384a37c 238 * operator or network events in which case it will be pseudo random
grzemich 0:d7bd7384a37c 239 * seeded by the real time clock.
grzemich 0:d7bd7384a37c 240 */
grzemich 0:d7bd7384a37c 241 u32_t
grzemich 0:d7bd7384a37c 242 avRandom()
grzemich 0:d7bd7384a37c 243 {
grzemich 0:d7bd7384a37c 244 return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
grzemich 0:d7bd7384a37c 245 }
grzemich 0:d7bd7384a37c 246
grzemich 0:d7bd7384a37c 247 #endif /* MD5_SUPPORT */
grzemich 0:d7bd7384a37c 248
grzemich 0:d7bd7384a37c 249 #endif /* PPP_SUPPORT */